“Most are not very big and they’re going very fast, so they break up in the atmosphere,” he said. “If they’re big enough to make a noise like the one in April they can be picked up by microphones that listen for nuclear tests.”

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Ruby said the majority of fireballs happen where people can’t see them.

“The earth gains 100 tons every day from meteorites hitting it,” he said.

“There are about 2,000 fireballs a day, just not where people see them. That people saw it in the daytime is rare. That they heard the sonic boom is

really rare.”

On April 23 a fireball crossed over Western Nevada in broad daylight, accompanied by a sonic boom. The meteor broke up over the Sierra foothills in California.

Before the April fireball, the last time a meteor was visible over Nevada was November 2009, when a fireball that could be seen by people between Reno and Salt Lake City, flew overhead.